Functional fluid compositions

ABSTRACT

FUNCTIONAL FLUID COMPOSITIONS COMPRISING A FLUID OF LUBRICATING OR HYDRAULIC VISCOSITY, SUCH AS A POLYPHENYL THIOETHER, MIXED POLYPHENYL OXY-THIOETHER OR MIXTURES THEREOF, AND A CORROSION INHIBITING AMOUNT OF AN AZOLE, WHICH COMPOSITIONS HAVE IMPROVED METAL COMPATIBILITY AND ARE PARTICULARLY USEFUL AS AIRCRAFT ENGINE LUBRICANTS AND HYDRAULIC FLUIDS.

United States Patent U.S. Cl. 252-47.5 4 Claims ABSTRACT OF THEDISCLOSURE Functional fluid compositions comprising a fluid oflubricating or hydraulic viscosity, such as a polyphenyl thioether,mixed polylphenyl oxy-thioether or mixtures thereof, and a corrosioninhibiting amount of an azole, which compositions have improved metalcompatibility and are particularly useful as aircraft engine lubricantsand hydraulic fluids.

This application is a continuation-in-part of application Ser. No.796,885, filed Feb. 5, 1969, now US. Pat. No. 3,591,500 dated July 6,1971, which in turn is a continuation-in-part of application Ser. No.540,488, filed Apr. 6, 1966, now abandoned.

This invention relates to functional fluid compositions having improvedmetal compatibility and more particularly to functional fluidscontaining certain organic nitrogen compounds.

Many different types of materials are utilized as functional fluids andfunctional fluids are used in many different types of applications. Suchfluids have been used as electronic coolants, atomic reactor coolants,diffusion pump fluids, synthetic lubricants, damping fluids, bases forgreases, force transmission fluids (hydraulic fluids) and as filtermediums for air-conditioning systems. Because of the wide variety ofapplications and the varied conditions under which functional fluids areutilized, the properties desired in a good functional fluid necessarilyvary with the particular application in which it is to be utilized witheach individual application requiring a functional fluid having aspecific class of properties.

Of the foregoing, the use of functional fluids as lubricants,particularly aircraft engine lubricants, has posed a difiicult area ofapplication. Present design trends in aircraft engines are to the purejet type or turbofan and away from the turboprop engine. Aside from themechanical differences in design between the turbofan and turbopropengines, there is a significant difference in the properties of thelubricants required for these engines, primarily because of increasedoperating temperatures. Furthermore, even within the area of turbofanengine design alone, there is a trend to increase the temperatures atwhich a lubricant must operate. Present temperature levels for turbofanlubricants are of the order of 400-450 F. (bulk oil temperature).However, it is evident that within the near future, temperatures of theorder of 500 F. or higher will be commonplace.

As the operating temperatures for lubricants have increased, it hasbecome exceedingly diflicult to find lubricants which properly functionat these higher temperatures for any satisfactory length of time.Furthermore, it should always be realized that while the operatingtemperatures generally referred to are bulk oil temperatures, the actualtemperatures at the points requiring lubrication exceed the bulk oiltemperature and often times are one hundred to several hundred degreeshigher.

In addition to the high temperature stability or durability problem,that is, the problem of findin a lubricant "ice which will be thermallyand oxidatively stable at temperatures as high as 500 F., the solutionof this problem is further complicated by the fact that in order for alubricant to be satisfactory for use in many aircraft engines, it mustalso be usable at temperatures as low as --20 F. to 0 F. It is,therefore, evident that present trends require lubricants having notonly an exceedingly wide liquid range but lubricants which are alsothermally and oxidatively stable at high temperatures. Furthermore,present and future lubricants must, of course, possess at least adequatetemperature-viscosity properties and satisfactory lubricity, that is thelubricants must not become too thin at the very high temperatures towhich they are subjected nor must they become too thick at the lowertemperatures and must at the same time be able to provide at leastminimum lubricity over such range of temperatures. In general, suchlubricants must also not be too volatile and even if somewhat volatilemust not, upon evaporation, leave any significant deposits to interferewith the proper operation of engine bearings.

Other properties which must be possessed by satisfactory jet enginelubricants are low pour point and relatively high flash point andautogenous ignition temperatures.

Another lubricating problem associated with presentday design and designtrends in jet engines is that the increased thrust needed to obtain highspeeds and altitudes results in further increases in not only operatingtemperatures but also higher bearing pressures.

A further problem in obtaining a lubricant which has good combination ofproperties at various temperatures is that those materials having a lowpour point also have a high evaporation rate at the temperatures of theorder of 400 F.-500 F.

In summary, as discussed above, a satisfactory jet engine lubricant mustpossess a wide variety of properties. Furthermore, all of theseproperties are not only diflicult to obtain in the same fluid but someof them tend to be mutually exclusive.

The most important properties for jet engine lubricants mentioned aboveare high temperature stability (thermal stability), high temperatureoxidative stability and little or no corrosion toward metals. Whilefluids are known which possess adequate thermal and oxidative stabilityeither inherently or can be provided by incorporating additives, manysuch functional fluids are corrosive to metals at high temperatures inthe order of 500 F. and in particular to copper and silver. Althoughmany additives, including organic nitrogen compounds, have been used inthe past to reduce or eliminate the tendency of lubricants to corrodemetals at lower temperatures, i.e., to 350 F., at the highertemperatures referred to above the properties of additives becomeunpredictable. Many previously known metal corrosion inhibitors are notactive at elevated temperatures and in many instances where they retaintheir corrosion inhibiting properties, they cause other problems such asdecreased thermal and oxidative stability.

Additives useful in many different chemical types of functional fluidshave now been discovered which reduce or eliminate the corrosiveness ofthe fluids toward metals at high temperatures.

It is, therefore, an object of this invention to provide functionalfluid compositions which are substantially noncorrosive to metals.Another object of this invention is to provide functional fluidcompositions which are substantially non-corrosive to metals at hightemperatures. Another object of this invention is to provide additivesfor functional fluids which when added in a small amount to a base stockwill reduce or eliminate the copper corrosivity of the fluid.

The objects mentioned above and others, which will hereinafter beapparent, are accomplished by adding to (A) a compound represented bythe formula wherein X is selected from the group consisting of hydrogen,NH and --OH, Y is selected from the group consisting of hydrogen, NH OHand NHO=N and G, G' and G" are each selected from the group consistingof carbon and nitrogen provided that at least 1 of G and G" is carbonand at least 2 of G are carbon, Z is selected from the group consistingof hydrogen and a hydrocarbon group, n is an integer from 1 to 2, m isan integer from 1 to 2 and the sum of m+n is equal to the number of Ggroups that are carbon (B) a compound represented by the formula where Gis selected from the group consisting of carbon and nitrogen providethat from 2 to 4 of G is nitrogen, X is selected from the groupconsisting of hydrogen, NH and OH, and p is an integer from to 2 and isnot greater than the number of carbon atoms in the ring represented byG.

(C) a compound represented by the formula where each R, R and R areselected from the group consisting of hydrogen and NH and (D) a compoundselected from the group consisting of cyanoamino hydroxy-pyridimines,anilinopropionitriles, aminocarbazols, aminopyridines, aminonicotinicacids, cyanoglutaramides, aminonaphthylimides and alkyldiimidazolines.

The hydrocarbon group, Z above, can be an aliphatic or aromatichydrocarbon.

Preferred additives of this invention are compounds of A aboverepresented by the formula (X)n LL compounds of A to D are presented inTable I hereinafter set forth.

The amount of the additives of this invention which are used infunctional fluids vary according to the nature of the particular fluidto which they are added, i.e., the amount is proportional to thecorrosivity of the fluid. Thus, the corrosivity of some fluids can besignificantly reduced or eliminated by the addition of as little asabout 0.025% by weight of the base stock of an additive of thisinvention. In general, an amount of up to about 5% by weight is adequateto achieve a substantially non-corrosive fluid. It is preferred to usefrom about 0.05% to about 0.5% by weight of an additive of thisinvention since within that range of concentrations the amount ofadditive used is low enough so that solubility considerations are notlimiting yet adequate corrosion inhibition is obtained.

Because of the various considerations which go into the choice of theamount of additive used and also because of the differences existingbetween the many fluids in which the additives of this invention areactive, the amount of additive to be used can be expressed as acorrosion reducing amount,, i.e., an amount which is effective toprovide decreased corrosivity of the fluids contemplated.

Since many of the additive of this invention have limited solubility insome of the fluids hereinafter described, the improved compositions ofthis invention can be prepared by dissolving the additive in a smallportion of the fluid at elevated temperautres in the range of from aboutF. to about 200 F., then mixing the heated composition with the mainportion of the fluid to form a composition of this invention.

The additives of this invention are particularly useful in polyphenylthioethers, which as used herein, means a compound or physical mixtureof compounds represented by the structures L in where m is a wholenumber of 0 to 6,

' }S-E flqt E I where A and A are each selected from oxygen and sulsumof x+y is from 1 to 6 and A and A are each selected where R is selectedfrom the group consisting of alkyl sisting of alkyl, haloalkyl andalkoxyl groups having from where x and y are whole numbers from 0 to 3and the sulfur, and

I I'T. I R lx @[Ahr U L in L l,

droxyl and hydrogen, T is selected from the group congroup consisting ofoxygen and sulfur provide at least one A is sulfur, y, m and n areintegers from 1 to 3 and K is an integer from to 1 providing at leastone K is 1.

Examples of such polyphenyl thioethers are:

Preferred compositions of this invention in which additives of thisinvention are advantageous are mixtures of m-bis(pheny1mercapto)benzeneand certain other materials which have properties that make them wellsuited for the uses disclosed above and particularly those applications,such as jet engine lubricants, requiring high temperatures, thermal andoxidative stability and wide liquid range. The other materialscontemplated to be used with m-bis (phenylmercapto)benzene to providesuch mixtures are as follows:

(a) The three-, four-, five-, and six-ring poly-phenyl thioethers, forexample, O-bis (phenylmercapto)benzene bis-(m-phenylmercaptophenyl)sulfide U U UTl m-phenylmercaptophenyl-p-phenylmercaptophenyl sulfide,

(IX) E Tet Tet Tet J the trisphenylmercaptobenzenes,

such as 1,2,4-trisphenylmercaptobenzene, 3,3-bis (phenylmereapto)biphenyl (XI) /s; As; m-bis(p-phenylmercaptophenylmercapto)benzene,(XII) m-bis(m-phenylmercaptophenylmercapto)benzene (XIII) E ISAC Tst TstTst and bis [m- (m-phenylmercaptophenylmercapto)phenyl] sulfide (XIV)O-st Tsi Tst Ist Tet (b) The mixed polyphenyl oxy-thioethers having theformula R-Y- R -Y -R wherein R is a phenyl group, R is a phenylene groupand Y and Y, are each selected from the group consisting of oxygen andsulfur, providing at least one of Y and Y is sulfur and m is a wholenumber from 1 to 4. Examples of such mixed polyphenyl oxythioethers aremphenylmercaptodiphenyl ether one 3,3-bis(phenylmercapto)diphenyl ether,

UUU O 3,3'-bis(plienoxy)diphenyl sulfide,

(moo

3-phenoxy-3'-pheny1mercaptodiphenyl sulfide,

(Till TO 3-phenylmercapto-3'-phenoxydiphenyl ether,

3 ,4'-bis (phenylmercapto diphenyl ether,

m-bis (m-phenylmercaptophenoxy) benzene,

and 3 phenylmercapto 3'-(m-phenylmercaptophenylmercapto) diphenyl ether,

Kl- O- O- Q- Q (c) The four-, liveand six-ring polyphenyl ethers whichcan be represented by the structure (XXIII) (XXIV) such as3,3'-bisphenoxy biphenyl such as 1,3,4-triphenoxybenzene (XXV) andmixture and combinations of (a) through (c).

The compounds (at) through (c) can be used alone or in combination toform compositions of this invention.

A typical mixture of polyphenyl thioethers is one which contains byweight from about 45% to about 55% m-phenyoxyphenylm-phenylmercaptophenyl sulfide, from about 25% to about 35%bis(m-phenylmercaptophenyl) sulfide and from about 18% to about 25%bis(m-phenoxyphenyl) sulfide. Particularly useful mixtures of polyphenylthioethers are those containing the above mixtures andm-bis(phenylmercapto) benzene in about equal proportions. Moreparticularly, examples of mixtures containing polyphenyl thioethers,mixed polyphenyl ethers, thioethers and halogenated polyphenyl etherswhich are suitable as lubricants under high temperature conditions areas follows in weight percent:

m (m Chlorophenylmercapto) m phenylmercapto benzene 46m-Bis(phenylmercapto)benzene 31 m-Phenoxy-m-phenylmercapto benzene 15m-Chlorodiphenyl sulfide 8 It is also contemplated that any of theindividual polyphenyl ethers described above or mixtures thereof inadmixture with additives of this invention can also be utilized toprovide compositions of this invention. For example, mixtures ofpolyphenyl ethers in which the nonterminal phenylene rings are linkedthrough oxygen atoms in the meta and/or para positions, have been foundto be particularly suitable. An example of such polyphenyl ethercompositions are those containing, in percent by weight, from about 0 to6% of O-bis(m-phenoxyphenoxy) benzene (1), about 40 to ofm-bis(m-phenoxyphenoxy)benzene (2), about 0 to 40% ofm-[(m-phenoxyphenoxy) (p-phenoxyphenoxy)]benzene (3), about 0 to 12% ofp-bis(m-phenoxyphenoxy)benzene (4), about 0 to 10% ofp-[(p-phenoxyphenoxy) (m-phenoxyphenoxy)] benzene (5), and about 0 to 6%of m-bis( henoxyphenoxy)benzene (6). Typical compositions of suchmixtures are listed below. The number of parentheses refers to thecompound mentioned above having the same number thereafter.

Mixtures, percent by weight, of components Con iponentz The action ofthe additives of this invention has been found to be beneficial in awide variety of synthetic functional fluids. Such fluids includesynthetic ester base fluids. These are fluids of lubricating viscositywhich are esters of alcohols containing at least 4 carbon atoms andwhich generally contain more than one ester group. They may bbe t1estersof polyhydric alcohols, of polybasic acids, or

Ester fluids with particularly advantageously low temperature viscosityproperties, which flow readily at temperatures as low as 30 C., areprovided by the diesters of dibasic acids. Ester lubricants of thedibasic acid ester type are illustrated by diesters of long-chaindicarboxylic acids like azelaic acid with long-chain branched primaryalcohols of the C to C range. The synthetic ester lubricants alsoinclude the esters of long-chain monobasic acids such as pelargonic acidwith glycols such as polyethylene glycols. Complex esters are alsoformed by linking dibasic acid half esters through a glycol such asdipropylene glycol, a polyethylene glycol of 200 molecular weight, andso forth. Permutation and combination of these methods of formingpolyester type lubricant fluids are valuable as well and also it iscommon practice to achieve desired properties in the ultimate base fluidby blending different polyester products. Simple esters providingsuitable fluids can be exemplified, for example, by bis(2- methylbutyl)sebacate, bis(l-methylcyclohexylmethyl) sebacate,bis(2,2,4-trimethylpentyl) sebacate, dipropylene glycol dipelargonate,the diesters of acids such as sebacid, azelaic and adipic acid withcomplex C -C primary branched chain alcohols such as those produced bythe oxo process, polyethylene glycol 200 bis(2-ethylhexyl) sebacate,diisoamyl adipate, 1,6-hexamethylene glycol di- (2-ethylhexanoate),bis(dimethylamyl) azelate and so forth.

Ester fluids with particularly good high temperature oxidationresistance are provided by neopentyl polyol esters. The alcohols fromwhich these esters are derived have the carbon structure of neopentane,with a central carbon atom surrounded by 4 substituent carbon atoms.Included in the neopentyl polyols are neopentyl glycol,trirnethylolethane, trimethylolpropane, pentaerythritol anddipentaerythritol. Generally, the base fluids comprising neopentylpolyol esters are the esters with monocarboxylic acids. Such esters aregenerally more oxidatively and thermally stable than the dibasic acidesters. The useful esters of the neopentyl polyols include, for example,the esters of trimethylol propane, neopentyl glycol, pentaerythritol anddipentaerythritol with normal, branched chain and mixed acids having thechain lengths varying from C to C Thus, an illustrative series of estersare trimethylolpropane tri-n-pelargonate, trimethylolpropane,tricaprate, trimethylolpropane tricaprylate, the trimethylolpropanetriester of mixed octanoates, pentaerythrityl tetra butyrate,pentaerythrityl tetravalerate, pentaerythrityl tetracaproate,pentaerythrityl dibutyrate dicaproate, pentaerythrityl butyrate caproatedivalerate, pentaerythrityl butyrate trivalerate, pentaerythritylbutyrate tricaproate, pentaterythrityl tributy-rate caproate and mixedtetraesters of C fatty acids. Suitable dipentaerythrityl esters includedipentaerythrityl hexabutyrate, dipentaerythrityl hexapropionate,dipentaerythrityl hexavalerate, dipentaerythrityl hexacaproate,dipentaerythrityl hexaheptoate, dipentaerythrityl hexacaprylate,dipentaerythrityl tributyrate tricaproate, dipentaterythrityltrivalerate trinonylate and other dipentaerythrityl mixed hexaesters ofC fatty acids. Also, additives of this invention are useful in mixturesof monoand dipentaterythritol esters of C fatty acids and mixtures of Cfatty acids.

For further description of still other ester fluids adapted for use aslubricant base stocks and useful in the provision of the compositions ofthis invention, reference may be made, for example, to the discussion inGunderson et al., Synthetic Lubricants" (Reinhold, 1962).

Other compositions of this invention useful as functional fluids can beprepared by combining additives of this invention described above withmonoand dialkylthiophenes represented by the structural formula whereinA, B and D are each alkyl C radicals and any two of A, B and R radicalstogether with the carbon atom to which they are attached can form analicyclic ring and m and n are integers from to 1, providing the sum ofm+n is at least one.

Typical thiophenes of structure XXVIII are as follows: 2,5l-hexyll-methylnonyl) thiophene, 2,4-( l-hexyl-1-methylnonyl)thiophene,2-tert-butyl thiophene, 2,5-tert-butyl thiophene, 2,5-1,1-dimethylpropyl) thiophene, 2,5-( l-butyll-octylnonyl) thiophene,2,5-( l-propylcyclobutyl)thiophene, 2-tert-butyl-4-l-octyl-l-methyloctadecyl) thiophene,

2,5 l-methylcyclohexyl) thiophene,

2,5 l-octyl- 1-methyldecyl) thiophene,

2,5- l, l-dimethyltridecyl) thiophene,

2,3-( 1,1-dimethyltridecyl)thiophene,

2,4-( l, l-dimethyltridecyl) thiophene,

2,4-( l-methylcyclopentyl) thiophene, and 2,5- l-n-dodecylopentyl)thiophene.

Othe functional fluids in which the additives of this invention can beused are blended synthetic fluids comprising a major proportion ofdihalogenated diphenyl ethers or sulfides and a minor amount of blendingagents selected from halogenated lower alkyl benzenes, halogenatedbenzene, monohalogenated diphenyl ethers and chlorinated biphenyl orcombinations thereof. The dihalogenated diphenyl ethers suitable for useas base stocks in the fluid compositions of this invention are thoserepresented by the structure where A is a chalkogen having an atomicnumber of 8 to 16, E and F are bromine, chlorine and fluorine.

Typical examples of such ethers and sulfides are:

(1) Different halogen on each ring (2) Same halogen on each ring2,2-dibromodiphenyl ether, 2,2'-dibromodiphenyl sulfide,2,3'-dibromophenyl ether, 2,3'-dibromodipheuyl sulfide,2,4'-difluorodiphenyl ether, 2,4'-difluorodipheny1 sulfide,3,3'-dibromodiphenyl ether, 3,3'-dibromodiphenyl sulfide,3,4'-dibromodiphenyl ether, 3,4'-dibromodiphenyl sulfide,4,4'-dibromodiphenyl ether, 4,4-dibromodiphenyl sulfide,2,2-dichlorodiphenyl ether, 2,2'-dichlorodiphenyl sulfide,2,3'-dichlorodiphenyl ether, 2,3'-dichlorodiphenyl sulfide,2,4-dichlorodiphenyl ether, 2,4-dichlorophenyl sulfde,3,3'-dichlorodiphenyl ether, 3,3-dichlorodiphenyl sulfide,3,4'-dichlorodiphenyl ether,

As used herein the term major amount of a fluid means that the amount ofa particular fluid in a specific formulation is at least equal to theamount of any particular blending agent in said formulation. On theother hand the term minor amount of a blending agent means that theamount of a particular blending agent in a specific formulation is nomore than the amount of any specific fluid-in said formulation.

The others are generally preferred over the sulfides because their lowermelting points make them usable in a wider numbr of applications and ofthe ethers, those in which the halogen substituents are in the3,4'-relationship are preferred for use in the compositions of thisinvention, because their low melting points are the lowest of all thefluids of this invention.

The blending agents which can be used include the halogenated loweralkyl (C benzenes containing 1 to halogens, such as4-bromomethylbenzene, 2-bromoethylbenzene, 4-bromopropylbenzene,4-chlorobutylbenzene, 2,4 dichloromethylbenzene, 2,3dibromoethylbenzene, 2,4-dibromoethylbenzene, 2,4-dichloroethylbenzene,2-fluoro-4-chloroethylbenzene, 2,5-dibromoethylbenzene,3,4-dibromoethylbenzene, 3,5-dibromopropylbenzene, 2,4-fluorobutylbenzene and the like. It is preferred to use thebromine-containing compounds because of the increased fire-resistanceobtained thereby. Further examples of halogenated alkyl benzenes aretn'- and tetra-chloroethylbenzene, triand tetrabromoethylbenzene,pentachloromethylbenzene, pentachloroethylbenzene,pentabromoethylbenzene, pentabromopropylbenzene, pentachlorobutylbenzeneand the like.

In addition to the use of specific compounds, there can be used amixture of halogenated alkyl benzenes such as the mixture of brominatedethyl benzenes disclosed in US. Pat. No. 2,257,903, which contain anaverage of two atoms of bromine per mole of ethyl benzene.

Other blending agents include the monohalogenated diphenyl ethers suchas 2-chlorodiphenyl ether, 3-chlorodiphenyl ether, 4-chlorodiphenylether, 3-bromodiphenyl ether and the like and chlorinated biphenyl whichis illustrated by the chlorinated biphenyl commercially available asproducts containing about 21%, 32%, 42%, 48%, 54% and 60% of combinedchlorine corresponding approximately to mono-, di-, tri-, tetra-,pentaand hexachlorobiphenyl, respectively. The expression chlorinatedbiphenyl containing a stated percentage of combined chlorine is usedherein as not only including these directly chlorinated products, butalso as blends of one or more chlorinated biphenyl whereby the totalchlorine content is broadly within the range of 20% to 60% preferablywith the range of 20% to 42% by weight. It is also preferred, in orderto obtain fluids having low crystallizing points, to use chlorinatedbiphenyl which has been isomerized, and preferably distilled thereafteraccording to the teachings of US. Pat. No. 3,068,297.

The halogenated benzenes which can be used as blending agents includechloroand bromobenzenes. The preferred chlorobenzenes are di-, triandtetrachlorobenzene and mixtures thereof. The preferred bromobenzenes aremono-, diand tribromobenzene and more particularly m-dibromobenzene.Typical examples of halogenated benzenes useful as blending agents areo-dichlorobenzene, m-dichlorobenzene, 1,2,3-trichlorobenzene,1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene,l,2,3,4-tetrachlorobenzene, l,2,3,S-tetrachlorobenzene, o-dibromobenzeneand 1,2,4-tribromobenzene.

Other blending agents which can be used are perhalogenated alkylcompounds such as hexachlorobutadiene.

Another class of functional fluids employed in preparing compositions ofthis invention are aliphatic hydrocarbon oils. Such oils are thoseobtained by super refining petroleum thereby producing a mixture ofsaturated aliphatic hydrocarbons or they can be produced synthetically.Preferred hydrocarbon oils useful in preparing compositions of thisinvention are those represented by the formula wherein R R R and R aresaturated hydrocarbon radicals having a combined total of from 4 tocarbon atoms. The number of variations of the R groups in Formula XXX isvery large, and dependent thereupon is the viscosity range of anyparticular fluid. To list by name the many compounds contemplated by theabove structure would unduly lengthen the present disclosure sotherefore the following named compounds conforming to Formula XXX areincluded herein only to point out the more commonly available and moredesirable members of the class of compounds and in no way is suchlisting intended to exclude other compounds conforming to said formula.Such exemplary compounds are 2,2,4-trimethylpentane,4,4,6-trimethylnonane, 7,9-dibutyl-7-methylpentadecane,

9,1 1-dihexyl-9-methylnonadecane, 11,13-dioctyl-l l-methyltricosane,13,15-didecyl-lS-methylheptacosane,

15 1 7-didodecyll 5 -methyldotriacontane, 4-ethyl-2,4-dimethylpentane,4-butyl-4,G-dimethylnonane, 7-methyl-7-butyl-9-ethylpentadecane,9-methyl-9-pentyl-1 l-propylnonadecane,

1 l-methyl-l l-hexyl- 1 3-tridecyltricosane,13-methyl-13-heptadecyl-15-nonylheptacosane, IS-methyll S-butyll7-hexyldotriacontane.

One of the major bench scale methods used for evaluating the corrosivityof a lubricant or hydraulic fluid is the procedure given in MIL-L-923 6Aaccording to which the lubricant to be treated is heated at a specifiedtemperature in the presence of certain metals and air and thecorrosivity determined by measuring the change in weight of the metals.

Various compositions of this invention were tested according to theprocedure of MH.-L9236A except that the temperature was held at 500 F.instead of 600 F. The metal specimens used were, as specified in saidprocedure, steel, copper, silver, titanium, magnesium alloy and aluminumalloy. However, only the results upon copper and silver are reportedsince the compositions tested had essentially no eifect on steel,titanium, magnesium alloy and aluminum alloy. The results observed usingthe above-described procedure are recorded in the table below. Thecorrosivity to metals was determined by weighing the metal specimensbefore and after the test. The weight difference in milligrams persquare centimeter of metal surface exposed to the fluid is reported.

To demonstrate the advantages of the anticorrosion activity of additivesof this invention, various additives were added to a fluid designated asFluid A. Fluid A was a mixture consisting, by weight, of about 50% ofm-bis- (phenylmercapto)benezne, about 25% of m-phenoxyphenylm-phenylmercaptophenyl sulfide, about 11% of his--(m-phenoxyphenyl)sulfide and about 14% ofbis(mphenylmercaptophenyl)sulfide. Table I below presents the dataobtained by employing 0.1%, by weight, of each additive in Fluid A whenthe composition was subjected to the above-described test.

,TABLE I TABLE III Metal weight change Additive rug/cm. coneentra-Copper tion, attack,

Additive Copper Silver 5 Base stock wt. percent mg./cm. None, control(average of 23 tests) 2. 39 67 Pentaerythritol tetraoctanoate 6. 70fi-aminoiudazole -.01 .29 D0 10 -0. 21 fi-aminnindmnln .01 .28Bis(phenylmercapto)benzene 3.3 7-aminoindazole 00 20 D0 025 0. 903-arnino-1,2,4trlazole 09 56 D0.-- +0. 10 3,5-diamino-1,2,4-triazole 0313 DO 20 -0. O2 amino4-earbamy1-3-pyrazoleacetie aci .01 .1O FluldB 0 2.80 2,4-dicyano-3-ethyl-3-methyl glutaramide 57 59 D 025 0. 964-amino-1,8-naphtha1imide 35 53 05 +0. 22 2,2'-octamethylenedi-2-imldazoline 04 31 10 +0. 14 Adenine-N-oxide --1. 02 257-arnino-l-v-trlazolo-(d)pyrimidine-- 01 22 5,7-diamino-l,2,6,8-tetrazaiudo1izine 21 -.02 n 04 In accordance with theabove data, it is evident that 5-hydroxy1ndole. -l. 27 273,6-diaminocarbazo1 some of the fluids, particularly thioethers andmixtures l P Y 19 of thioethers, when used as lubricants for gas turbine2-am1non1cotimc ac1d .37 -.39 7-aminos-maz 1 1,5- 4 E35 engines areoutstanding with respect to high temperature -gfisg i ggg g(aggg -a =23-33 stability and metal fluid compatibility when combined 4,5.di,m,'n-mian f j -1 -1 with additives of this invention. Thus, this inventionreggg glgy n gz 2% lates to a novel method of lubricating gas turbineengines Ryan, 53 l fig fgiaii' j j j 1 which comprises maintaining onthe bearings and other fi-q g y rq vg y ig g s -fg wag points of wear ofthe engine a lubricating amount of a ,i,j.tii tfig i ,g g g ggi gggg j jcomposition of this invention. Other fluids containing Y y; hvB-tIiaZaiHdOIiZiH 25 an additlve of this invention useful as gas turbineengine tl-hydroxyindozole 04 1 .05 concentration.

TABLE II Metal weight change, rug/cm.

Additive Copper Silver Control, from above 2. 39 67 G-aminouraeil.-.--2. 6 74 5-aminouracil 3. 1 48 2, 7-dimercapto+hydrox ypyrimido(4, 5-b)pyrimi 5. 4 81 Ben imidamln 3, 7 1, 2 2-phenyl-4, G-bis(3-aminophenyD-1, 3, S-triazine 2. 8 07 Z-meroaptopyrimidine 4. 4 -1. 54, 6dihydroxy-Z-mercaptopyrimidine 6. 2 1. l4-a1nino-fi-hydroxy-Zmercaptopyrimidine. 6. 2 93 2-amino-4,6-dihydroxyprimidine 3. 4 61 l-3-(6-chlor0pyridazinyl) 3-3, 4-dichlorophyl) urea 5. 9 1. 7 3-methyl-5-phenyl pyrazole 8. 4 2. 0 2-hydroxy-8,3-4,4, 5, 6-hexachloroearbanilide 8. 8 3. 1 (3,4-dichlorophenylureido)p-menthane 3. 0 69 S-nitr 84 1. 4

A comparison of the results obtained in Tables I and II above indicatesthe selectivity required in solving the problem of metal corrosion byfunctional fluids at high temperatures by the incorporation ofadditives. Many additives which because of their structural similaritywould be expected to reduce metal attack are found to increase it underthe high temperature conditions for which the compositions of thisinvention are particularly useful.

In Table III below the results obtained using the above-described testare presented wherein fluids are employed containing S-aminoindazole,one of the preferred additives of this invention. Also included are theresults obtained with different amounts of S-aminoindazole employed inother fluids. The fluid designated Fluid B in Table III is a mixtureconsisting, by weight, of about 50% of m-phenoxyphenylm-phenylmercaptophenyl sulfide, about 22% of his (phenoxyphenyl)sulfideand about 28% of bis(m-phenylmercaptophenyl)sulfide. The concentrationof the additive is given in weight percent of the fluid and the copperattack is reported as weight change in milligrams per unit of surfacearea in contact with the fluid.

lubricants are neopentyl polyol esters of C fatty acids, mixtures ofneopentyl polyol esters of 0 fatty acids, dipentaerythritol ester of 0fatty acids and mixtures of the pentaerythritol esters anddipentaerythritol esters. Especially useful as gas turbine enginelubricants are mixtures of polyphenyl ethers and polyphenyl thioetherscontaining corrosive reducing amounts of an additive of this invention.

As a result of the excellent physical properties of the compositionsparticularly described above, improved bydraulic pressure devices can beprepared in accordance with this invention which comprise in combinationa fluid chamber and an actuating fluid in said chamber, said fluidcomprising a mixture of one or more of the base stocks hereinbeforedescribed. In such a hydraulic apparatus wherein a movable member isactuated by the abovedescribed functional fluids, performancecharacteristics are obtainable which are superior to those heretoforeobtainable.

Because of the excellent fire-resistance of the compositions of thisinvention, their exceptionally low pour points, and good lubricity, thefunctional fluids of this invention can be utilized in those hydraulicsystems wherein power must be transmitted and frictional parts of thesystem lubricated by the hydraulic fluid utilized. Thus, the novelcomposition of this invention finds utility in the transmission of powerin a hydraulic system having a pump therein supplying the power for thesystem. In such a system, the parts which are so lubricated include thefrictional surfaces of the source of power, namely the pump, valves,operating pistons and cylinders, fluid motors and in some cases, formachine tools, the ways, table and slides. The hydraulic system may beof either the constant-volume or the variable-volume type of system. Thepumps may be of various types, including the pistontype pump, moreparticularly the variable-stroke piston pump, the variable-discharge orvariable displacement piston pump, radial-piston pump, axial-pistonpump, in which a pivoted cylinder block is adjusted at various angleswith the piston assembly, for example, the Vickers Axial-Piston Pump, orin which the mechanism which drives the pistons is set at an angleadjustable with the cylinder block; gear-type pump, which may be spur,helical or herringbone gears, variations of internal gears, or a screwpump; or vane pumps. The valves may be stop valves, reversing valves,pilot valves, throttling valves, sequence valves or relief valves. Fluidmotors are usually constantor variable-discharge piston pumps caused torotate by the pressure of the hydraulic fluid of the system with thepower supplied by the pump power source. Such a hydraulic motor may beused in connection with 15 a variable-discharge pump to form avariable-speed transmission.

Although the composition described above are generally quite suitablefor most applications, it may also be desirable to add small amounts ofvarious other functional addition agents such as viscosity indeximprovers, e.g., a polymerized methacrylate ester, an alkylatedpolystyrene, or the polyether condensation products of ethylene oxide orpropylene oxide, or both, with a glycol such as ethylene glycol,propylene glycol, butanediol, etc., or with an aliphatic alcohol such asbutanol, octanol, decanol, tridecanol, etc., pour point depressants,oxidation inhibitors, detergents, corrosionand rust-inhibting agents,anti-wear and lubricity agents, anti-foaming agents such as the siliconepolymers, and the like.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

The embodiments of this invention in which a particular property orprivilege is claimed are defined as follows:

1. Composition comprising (I) a major amount of a fluid of lubricatingor hydraulic viscosity selected from the group consisting of (i)polyphenyl thioethers, (ii) mixed polyphenyl oxy-thioethers, and (iii)admixtures thereof, and

(II) a corrosion inhibiting amount of a triazole of the formulaReferences Cited UNITED STATES PATENTS 2,160,293 5/1939 Shoemaker et a1.252-5:1.5 RX

2,197,834 4/1940 Reiff et a1 252-35 X FOREIGN PATENTS 851,651 10/1960Great Britain 252-52 DANIEL E. WYMAN, Primary Examiner W. H. CANNON,Assistant Examiner US. Cl. XrR.

